The present invention relates to a novel machine and method for applying pressure or snap fasteners on a support, such as, for example, a fabric material.
The field of the invention is that of the machine designed for automatically applying snap fasteners, either made of a metal material or not, and other fittings in general such as rivets, eyelets and the like, on support materials such as fabric, leather, paperboard, plastics materials and the like.
In this type of machine it is very important that the two portions forming the snap fastener be mutually clamped by pressure, the so-called xe2x80x9crivetingxe2x80x9d pressure, which is necessary to hold the snap fastener on its support material, such as a fabric material, without damaging the support material because of an excessive effort.
Moreover, it is very important to prevent reduced pressures of efforts which could lock the snap fastener with an insufficient locking or clamping force.
On the other hand, the above mentioned operating pressure would be undesirably modified if, because of a changing of the support material thickness, a corresponding variation of the punch element displacements applying the snap fastener portions would not be carried out: in other words, a larger operating displacement or stroke for smaller thicknesses and vice versa.
In prior art machines, the above mentioned requirements was met by providing specifically designed systems, such as microswitches or measurement sensors, provided for detecting the displacement or stroke amount of a bottom punch element which, in such an application, would be provided to yield depending on the thickness of the support material to which the two portions of the snap fasteners must be connected.
Thus, conventional automatic machines for applying snap fasteners, provides to use a riveting pressure which is indirectly determined, i.e. set depending on the yielding of the punch element under the pressure applied thereby onto the supporting material.
The above mentioned systems, however, have the drawback that the disclosed displacement of the punch element would change, for example because of a wear of movable portions or the like, from a set displacement, then the riveting pressure would be consequently undesirably modified to values which would be unsuitable for properly applying the snap fastener on the supporting fabric.
Moreover, prior machines are suitable to detect only the maximum riveting pressure, and are not designed to also detect the minimum riveting pressure value.
Thus, even if it is assured that the two portions of the snap fastener are not pressed with an excessive force on the supporting fabric, on the other hand it is possible that the minimum value of the riveting pressure is not achieved, which minimum value would be indispensable for preventing the snap fastener portions from detaching from the supporting fabric or material.
Accordingly, the main object of the present invention is to provide a novel machine and method for automatically applying snap or pressure fasteners on a support material and which, differently from prior approaches, are specifically designed for applying the snap fasteners with a proper value of the riveting pressure, also in an even and time repeatable manner.
Another object of the present invention is to provide a delivery device for automatic machines applying snap fasteners and other metal fittings in general.
Actually, prior snap fastener applying machines conventionally comprise a snap fastener or fitting delivery device including:
a vessel for holding therein the snap fasteners to be supplied;
a feeding and supplying system for feeding and supplying said snap fasteners to a delivery guide means, including either a rotary bell, or a vibrating means, or a swinging arm mechanism;
at least a delivery guide means, for sending the individual snap fasteners to a gripper supplying assembly;
a gripper supplying assembly including a plurality of loading rods for loading the individual snap fasteners toward a gripper and punch region to apply said snap fasteners to a fabric and the like material.
These prior machines are affected by several different drawbacks.
At, first, a missing snap fastener in a gripper (for example a male portion of the snap fastener in a top gripper), will cause an application of only a counter-male portion, with a consequent damaging of the fabric material due both to a mechanical action deriving from the applied snap fastener portion and an operation of the operator which must remove from the fabric material said counter-male element already fixed on said fabric.
Further drawback is that missing snap fasteners at the end portion of the guide means, due either to an empty condition of the snap fastener feeding vessel or to possible malfunctions and/or lockings inside the guide means.
In this case, it would be very important to collect information about the missing said snap fasteners at the end portion of the guide means, and to collect any further information due to possible jammings.
In the case of an excessively filled vessel, a further drawback would occur, i.e. that of not sufficiently supplying the snap fasteners in their guide means.
Thus, yet another main object of the present invention is to provide a delivery device and related automatic machine for applying snap fasteners, allowing an operator to apply said snap fasteners with high quality operations, thereby protecting the end product from any damages due to not properly feeding the snap fasteners or due to an application of damaged snap fasteners during their delivery step.
The above mentioned objects, as well as yet other objects, are achieved respectively by the machine and method as described herein.
Preferred embodiments of the invention are disclosed in the dependent claims.
The above mentioned objects, features and advantages of the invention will become more apparent hereinafter from the following detailed disclosure of a preferred embodiment of the machine according to the invention, which has been disclosed, by way of an exemplary but not limitative embodiment, in the figures of the accompanying drawings.